organic chemistry positive and negative test.

[wkawk2416]

hello, I just need a help with some tests.

I know that we have to know cloroform test, silver mirror test, idoform test, 2-4 DNP test, and what else there that we have to know?

could someone list tests and how we can use that to differenciate the functional groups!

Thanks and good luck studying!👍👍

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[harrygt]

hello, I just need a help with some tests.

I know that we have to know cloroform test, silver mirror test, idoform test, 2-4 DNP test, and what else there that we have to know?

could someone list tests and how we can use that to differenciate the functional groups!

Thanks and good luck studying!👍👍

Can you please make a short description of the 4 tests[I already know them] you just mentioned, and then explain their application? It would be great, and I will add a few more.

 

[wkawk2416]

🙂sure, let me add as far as i know

Tollens ( silver mirror) is positive when aldehyde or keto alpha alchol is present

idoform is positive when ketone or secondary alcohol

2,4 DNP is positive if there is a carbonyl group.

This is all I know.

Please correct me if i am wrong and add more

 

[pistolpete007]

so does that mean if uf have a positive iodoform test u also have a post 2,4 dnp and and positve tollen test?

 

[wkawk2416]

well something like that

if you have carbonyl C=O, then you will always have a positive result for 2,4 DNP test.

HOwever, if you have ketone, then you will have a negative result for tollens but positive for idoform.

Remember tollen is positive when there is aldehyde or ketone that has alpha alcohol group, but if there is a ketone group, you will get a negative result for tollen test.

can someone please confirm these?

 

[harrygt]

well something like that

if you have carbonyl C=O, then you will always have a positive result for 2,4 DNP test.

HOwever, if you have ketone, then you will have a negative result for tollens but positive for idoform.

Remember tollen is positive when there is aldehyde or ketone that has alpha alcohol group, but if there is a ketone group, you will get a negative result for tollen test.

can someone please confirm these?

Yes, what you said is confimred!
BTW, I would like to point out in order to get a positive test with Iodoform reaction, you have to have a methl connected to the carbonyl or the secondary alcohol carbon. Not every ketone will give you a positive Iodoform test.

I would also like to add the Benedict's test. It's kinda like the tollen's test used to identify reducing sugars. The oxidizing agent in Benedict's reagent is Cu 2+. Reducing sugars: All monosaccharides + lactose and maltose

 

[harrygt]

Yes, what you said is confimred!
BTW, I would like to point out in order to get a positive test with Iodoform reaction, you have to have a methl connected to the carbonyl or the secondary alcohol carbon. Not every ketone will give you a positive Iodoform test.

I would also like to add the Benedict's test. It's kinda like the tollen's test used to identify reducing sugars. The oxidizing agent in Benedict's reagent is Cu 2+. Reducing sugars: All monosaccharides + lactose and maltose

I will add a couple more once I get home and check my notebood. I remember some stuff.

 

[adizzle87]

Can the Iodoform test work on aldehydes?

 

[gentile1225]

also, KMnO4 test for aldehydes and ketones.

 

[adizzle87]

also, KMnO4 test for aldehydes and ketones.

How does it do that?

 

[OnlyDrilling]

Im pretty sure iodoform is for methyl ketones only